A. Field of the Invention
The invention relates to the production of adiponitrile from acrylonitrile by electrochemical synthesis, and particularly to an improvement in such a process wherein the cathodes are pretreated with phosphoric acid.
B. Background of the Invention
The reduction of acrylonitrile to adiponitrile by electrohydrodimerization is taught in British Pat. No. 1,089,707 (to Tomilov). In such a reaction, it is often preferred to use cathodic surface metals selected for high hydrogen over-voltage, and although metals such as lead, thallium, zinc, mercury and cadmium are preferred, because of the expense of the material and the lack of strength of these materials, it is common practice to electroplate the desired metal on a more suitable metal such as steel which is strong, readily available and inexpensive. A suitable cathode, for example, for the electrohydrodimerization of acrylonitrile to adiponitrile is cadmium-plated steel.